Biomedical subjects

A Dittmar

Publications and source records attributed to A Dittmar.

At least 37 records · Page 2Linked to original sources

PubMed1997

Autonomic nervous system response patterns specificity to basic emotions.

The aim of this study was to test the assumption that the autonomic nervous system responses to emotional stimuli are specific. A series of six slides was randomly presented to the subjects while six autonomic nervous system (ANS) parameters were recorded: skin conductance, skin potential, skin resistance, skin blood flow, skin temperature and instantaneous respiratory frequency. Each slide induced a basic emotion: happiness, surprise, anger, fear, sadness and disgust. Results have been first considered with reference to electrodermal responses (EDR) and secondly through thermo-vascular and respiratory variations. Classical as well as original indices were used to quantify autonomic responses. The six basic emotions were distinguished by Friedman variance analysis. Thus, ANS values corresponding to each emotion were compared two-by-two. EDR distinguished 13 emotion-pairs out of 15. 10 emotion-pairs were separated by skin resistance as well as skin conductance ohmic perturbation duration indices whereas conductance amplitude was only capable of distinguishing 7 emotion-pairs. Skin potential responses distinguished surprise and fear from sadness, and fear from disgust, according to their elementary pattern analysis in form and sign. Two-by-two comparisons of skin temperature, skin blood flow (estimated by the new non-oscillary duration index) and instantaneous respiratory frequency, enabled the distinction of 14 emotion-pairs out of 15. 9 emotion-pairs were distinguished by the non-oscillatory duration index values. Skin temperature was demonstrated to be different i.e. positive versus negative in response to anger and fear. The instantaneous respiratory frequency perturbation duration index was the only one capable of separating sadness from disgust. From the six ANS parameters study, different autonomic patterns were identified, each characterizing one of the six basic emotion used as inducing signals. No index alone, nor group of parameters (EDR and thermovascular for instance) were capable of distinguishing each emotion from another. However, electrodermal, thermo-vascular and respiratory responses taken as a whole, redundantly separated each emotion thus demonstrating the specificity of autonomic patterns.

Adult↗

PubMed1997

Basic emotions evoked by odorants: comparison between autonomic responses and self-evaluation.

The present study was designed to analyze the relationship between self-report and physiological expression of basic emotions (happiness, surprise, fear, sadness, disgust and anger) in response to odorants. 44 subjects inhaled five odorants: vanillin, menthol, eugenol, methyl methacrylate, and propionic acid. Six autonomic nervous systems (ANS) parameters were simultaneously recorded in real time and without interference: Skin Potential (SP), Skin Resistance (SR), Skin Temperature (ST), Skin Blood Flow (SBF), Instantaneous Respiratory Frequency (IRF) and Instantaneous Heart Rate (IHR). At the end of the recording, subjects were instructed i) to identify the odorants roughly II) to situate them on an 11-point hedonic scale from highly pleasant (0) to highly unpleasant (10); and iii) to define what type of basic emotion was evoked by each odorant. In this study, the expected affects were aroused in the subjects. Vanillin and menthol were rated pleasant, while methyl methacrylate and propionic acid were judged unpleasant. Eugenol was median in hedonic estimation. ANS evaluation (each autonomic pattern induced by an odorant was transcripted into a basic emotion) shows that pleasantly connoted odorants evoked mainly happiness and surprise, but that unpleasant ones induced mainly disgust and anger. Eugenol was associated with positive and negative affects. Comparison between conscious (verbal) and unconscious (ANS) emotions, reveals that these two estimations 1) were not significantly different as far as the two pleasant odorants were concerned, 2) showed a tendency to be significantly different for eugenol odorant which was variably scored on the hedonic axis, and 3) exhibited a significant difference for the two unpleasant odorants, for which the corresponding "verbal emotion" was mainly "disgust", while the most frequent ANS emotion was "anger". In conclusion, these results show quite a good correlation between verbal and ANS estimated basic emotions. The main difference concerns anger: while there is a high occurrence of this emotion revealed by the analysis of ANS responses, it does not appear to be easily expressed through the verbal channel.

Adult↗

PubMed1997

Odor hedonics: connection with emotional response estimated by autonomic parameters.

The aim of this paper is to analyse the relationship between self-report hedonic evaluations and the physiological expression of emotion in response to odorants. We try to solve the following questions: (1) Is it possible to find any experimental evidence that the sense of smell is linked with emotion? (2) What kind of odorants can be distinguished by autonomic analysis? (3) Is there a link between hedonics and autonomic information? The effects of odorants on the emotional process were estimated, in terms of autonomic nervous system (ANS) activity. Fifteen subjects inhaled five odorants as olfactory stimuli: lavender (LAV), ethyl acetoacetate (EAA), camphor (CAM), acetic acid (AA) and butyric acid (BA). After inhaling the odorant, subjects were requested to fill out an 11-point hedonic scale to rate its pleasantness versus unpleasantness. ANS parameters were as follows: two electrodermal responses, skin potential (SP) and resistance (SR); two thermovascular parameters, skin blood flow (SBF) and skin temperature (ST); and two cardiorespiratory parameters; instantaneous respiratory frequency (IRF) and instantaneous heart rate (IHR). Simultaneous recording of six parameters showed that specific autonomic patterns were associated with each odorant. An analysis of variance made it possible to differentiate among the five odorants. Two-by-two odorant comparisons for autonomic responses using Tukey's HSD multiple comparison test only permitted differentiation between pleasant odorants (LAV and EAA) and unpleasant (AA and BA) ones, but camphor was differentiated from both pleasant and unpleasant odorants. Each odorant elicited responses in the different parameters, yet subjects responded through their preferential channels; an average of two channels was used by each subject. These results when compared with those obtained with other senses (visual and auditory), did not evidence the postulated preferential link between olfaction and emotion. A strong link between hedonics and ANS response could be demonstrated when considering each subject and mainly through his/her preferential channel(s); conversely a weak correlation (SR duration excepted) was obtained between inter-subjects' hedonic evaluation. It seems that for a given population the autonomic response reflect the odor valence only through some parameters related to the main preferential channel(s) and thus the global autonomic pattern has to be considered.

Acetic Acid↗

PubMed1997

Impact of profile haemodialysis on intra-/extracellular fluid shifts and the release of vasoactive hormones in elderly patients on regular dialysis treatment.

In 15 patients with end-stage renal failure and proven coronary heart disease, profile haemodialysis with decreasing ultrafiltration rate and hyperionic, decreasing dialysate solute concentration was compared with conventional, extracorporeal bicarbonate haemodialysis (Na+D = 138 mmol/l). Body fluid distribution and the release of vasoactive hormones (plasma renin activity, aldosterone, norepinephrine, epinephrine, and atrial natriuretic peptide) were investigated. Haemodialysis with constant ultrafiltration rate and constant dialysate composition (A) was followed by two dialysis profiles: decreasing ultrafiltration rate (B) and additional hyperionic, decreasing dialysate sodium concentration (C). In all 15 patients, the dialysis procedures (A) - (C) were used for 2 weeks each with six sessions, the last being taken for investigation. Body fluid distribution was calculated. In patients with serum sodium above 136 mmol/l, the conventional dialysis (A) as well as the Uf profile (B) showed a net fluid shift from extracellular volume (ECV) to intracellular volume (ICV). Using the profile with hyperionic, decreasing Na+D (C), the reverse fluid shift with decreasing ICV was achieved not only in those with serum Na+ <136 mmol/l, but also in those with serum Na+ > or = 136 mmol/l. The release of vasoactive hormones decreased already at profile haemodialysis (B) compared with (A) and was further reduced in (C). These results would suggest, profile dialyses B and C to have less impact on the cardiovascular system in elderly patients assuming higher patient comfort compared with the standard dialysis procedure. A higher benefit was obtained in C compared with B, presumably due to the additional prevention of the ICV shift and plasma volume depletion in patients with initial serum sodium > or = 136 mmol/l using transiently hyperionic Na+D. These results show that in elderly patients, hyperionic profile haemodialysis (Na+D > Na+S) had less impact on cardiovascular regulation than conventional bicarbonate dialysis.

Aged↗

PubMed1995

Increased activation as a limiting factor of performance in sharp shooters.

The measurement of autonomic nervous system (ANS) activity was performed on 10 male and five female sharp shooters (rifle) during competitions. Electrodermal, thermovascular, cardiorespiratory variables and two indices of performance were recorded simultaneously. When the subjects fired shots that hit the target, they had a higher number of negative skin potential responses than when they missed. The responses had lower amplitude but lasted longer than when the shots missed the target. Good performance seemed to depend on high levels of motivation (increase in negative potential response), better mastery of the emotional reactivity (low amplitude response), and greater concentration time (increased duration of response).

Autonomic Nervous System↗

PubMed1995

The ohmic perturbation duration, an original temporal index to quantify electrodermal responses.

The reactivity of the autonomic nervous system was (D.C.) recorded using six parameters simultaneously. Such a device permitted to describe a new index of skin resistance response (SRR). The ohmic perturbation duration (O.P.D. index) was defined as the period during which the subject is effectively responding to the stimulation. O.P.D. index was easily quantified because the specific part of the response, showing many fluctuations at a low resistance level, can be distinguished from the recovery part without fluctuations or with smaller microevents of different kinds. Moreover, the slope of this fluctuation is identical to that observed just before the stimulation. The comparison between the values of the O.P.D. index and classically used SRR durations enabled us to calculate the identity percentages from five other neurovegetative parameters. Results showed high values for the skin potential (91%) and skin blood flow (82.5%). These values were smaller as far as skin superficial temperature (50.5%), heart (40.8%) and respiratory (46.5%) variations were concerned. Nonetheless these last three percentages were still higher than those usually obtained with the values of the correlation coefficients from different, simultaneously recorded parameters. O.P.D. index comparison with four other classical used temporal indices (recovery time, 1/3, 1/2 and 2/3 of the recovery time) show a high significant concordance in O.P.D. index opposed to aleatory one obtained with these four other durations. Thus, the O.P.D. index could be an appropriate measure of electrodermal response (EDA) allowing any stimulus to be temporarily quantified towards sympathetic activation induced response.

Adult↗

PubMed1995

Bioelectric and microcirculation cutaneous sensors for the study of vigilance and emotional response during tasks and tests.

Bioelectronic phenomena related to the activity of the Autonomic Nervous System (ANS) activity mainly take place in the deep part of the brain where they are difficult to record. The hand skin, being richly innervated by sympathetic efferent fibres, offers an interface from which relevant ANS-related signals can be recorded. Two non-invasive bioelectronic measurements (skin resistance and potential) reflecting the activity of the ANS were performed at the skin surface. These measurements were complemented by thermovascular (skin microcirculation and skin temperature) and cardiorespiratory (instantaneous heart rate and instantaneous respiratory frequency) measurements. The bioelectric measurements were performed using noninvasive Ag/AgCl electrodes. Non-metallic NASICON (Na Super Ionic Conductor) electrodes were tested and compared with traditional electrodes for the optimization of bioelectric measurements. Signal analysis and data processing was accomplished by means of original indices on a specially designed PC-based software. The methodology was used to evaluate vigilance level, mental workload, and emotional response during tasks (sporting activity, mental calculation, olfactive stimuli) and in critical situations (car crash avoidance).

Accidents, Traffic↗

PubMed1994

Autonomic responses correlate to motor anticipation.

New findings have stated that autonomic nervous system (ANS) functioning may reflect some cognitive processes observed in real time analysis. Four ANS variables plus instantaneous heart rate and respiratory frequency were quantified by original techniques and indices on 11 subjects during a coincidence-anticipation task, performed on a computer screen under six different, randomly-presented modalities (3 modalities describing the spot moving along a parabola at 2 speeds). Tonic levels and phasic responses corresponding to each trial were recorded continuously. Results showed that skin resistance tonic level evolution gave evidence of vigilance changes. Thus, performance can be related to subjects' vigilance. An autonomic response was always observed during performance of an anticipation task. The six task modalities were distinguished by performance values. Simultaneously recorded ANS responses fully differentiated these same modalities for 10 subjects out of 11. These ANS responses were furthermore related to performance. Ten subjects out of 11 possess at least one Autonomic variable which can differentiate the six task modalities, confirming Lacey's hypothesis on ANS preferential response, and suggesting ANS specificity. ANS functioning may reveal some brain functions through a specific autonomic channel, characterizing each subject. The behavioral output of an individual may thus be reflected by such a functioning.

Adolescent↗

PubMed1994

Comparison of different techniques of hypothermic pig heart preservation.

The aim of this study was to compare several methods of hypothermic heart preservation. Isolated pig hearts were preserved for 24 hours in cold cardioplegic solution (St. Thomas' Hospital modified solution) by continuous perfusion (group I), microperfusion (group II), or simple storage (group III). The findings were then compared with those from hearts harvested and immediately reperfused (the control group). Group III hearts showed lower adenosine triphosphate preservation (0.47 +/- 0.18 mumol/g) than did group I and II hearts and the control hearts (1.86 +/- 0.40, 1.98 +/- 0.27, and 1.84 +/- 0.55 mumol/kg, respectively). Electronic microscopy studies also revealed that the myocardial cells in the group III hearts appeared to be damaged. After the hearts had undergone preservation, myocardial function was studied for 60 minutes under nonworking conditions using an ex vivo functional testing system. For group III, the mean left ventricular developed pressure and ventricular compliance (16 +/- 22 and 63 +/- 48 mm Hg, respectively) differed significantly from those for group I (83 +/- 26 and 0 +/- 0 mm Hg, respectively), group II (83 +/- 33 and 14 +/- 18 mm Hg, respectively), and the control group (115 +/- 13 and 0 +/- 0 mm Hg, respectively). We concluded from our findings that perfusion methods are superior to cold storage but inadequate to maintain heart viability for the long term during hypothermia. These techniques must be improved before they can be adopted for clinical use.

Adenine Nucleotides↗

PubMed1994

Thermal diffusion probe and instrument system for tissue blood flow measurements: validation in phantoms and in vivo organs.

A minimally invasive probe and instrument system for real-time measurements of temperature, thermal conductivity and tissue blood flow has been designed for research and clinical use. The essence of the probe is a thermistor, located at the tip of catheters or glass and steel needles, and operating in transient self-heated mode at constant temperature increment. Thermal conductivity and tissue blood flow are determined by use of a coupled tissue-probe thermal model. The effects of temporal baseline temperature shifts are minimized by a novel, automatic, analog compensation circuit. Very short heating periods (3 s) and cooling periods (12 s) provided near-continuous measurements (4/min). Calibration experiments performed in media of known thermal conductivity exhibit a linear response with respect to thermal conductivity. In vitro experiments performed in isolated perfused dog liver preparations are presented to evaluate this instrument system. In vivo experiments performed in cat brain, dog liver, and human tumor demonstrate the ability of this instrument system to perform physiologically valid measurements (comparison inter-subjects and intra-subjects). The minimally invasive probes (0.8 mm OD) are capable of long term measurements (several months), with minimal tissue reactions (0.3 mm around the probe).

Animals↗

PubMed1993

Quantitative reduction of MTT by hearts biopsies in vitro is an index of viability.

The aim of this study is to evaluate the use of tetrazolium reductase (TR) activity as an indicator of myocardial viability in an isolated arrested pig heart biopsy model. Methyl Tetrazolium (MTT) is cleaved by an enzyme in the presence of coenzymes NAD, NADP. Cleavage yields a highly colored formazan product which is DMSO soluble. Efficient bioreduction of MTT has been investigated with heart biopsies. The relationship between MTT reduction and (1) oxygen consumption (r = 0.96, P < 0.001), (2) the sum of the adenine nucleotide levels (r = 0.87, P < 0.001) and (3) localization of coloration, has been established. The use of MTT in colorimetric assays offers high sensitivity. MTT reduction is a valid method. It is rapid and reproducible, and can be used as an indicator of myocardial viability. The MTT test has been used to rapidly compare the effect of different cardioplegic solutions (St Thomas and improved St Thomas) on hypothermic cardiac preservation. Significant differences have been established between the two solutions (P < 0.01).

Adenine Nucleotides↗

PubMed1993

A model of sporting performance constructed from autonomic nervous system responses.

Four autonomic nervous system (ANS) variables: skin potential and resistance, skin blood flow and temperature - plus instantaneous heart rate and respiratory frequency - were simultaneously recorded during sporting competitions. The performances of 15 marksmen and 7 archers were analysed by comparing the variations in the six parameters during a concentration phase prior to shooting and during the shooting (or active) phase proper. The results of the performances distinguished two groups of sportsmen: firstly, the best shots and secondly, the worst shots. Comparison of the autonomic responses between the groups showed statistically significant correlations among the ANS variables. This made possible a relationship between performance characteristics and a percepto-effector factor to be defined. More precisely, this factor was defined as the number of correlations of the measured variables in the two phases, concentration and shooting. A positive relationship was demonstrated--the higher the factor, the better the performance. In addition, the stability of the factor was greater within the best marksmen and archers group. A model of the temporal change of the percepto-effector factor in both groups was given in three dimensions. This modelling of performance characteristics gave a visual indication of the differences between best/worst performances.

Autonomic Nervous System↗

PubMed1993

Increased role of skeletal muscle in the calorigenic response to glucagon of cold-acclimated ducklings.

The site of the calorigenesis observed in birds after glucagon was sought in control and cold-acclimated (CA) ducklings. Twenty-four 6-wk-old muscovy ducklings were reared either at thermoneutrality (TN) (25 degrees C) or in the cold (4 degrees C) from the age of 1 wk. Glucagon-induced calorigenesis (GIC) was estimated at 25 degrees C after a peritoneal glucagon injection (103 nmol/kg). Glucagon induced a higher increase in animal heat production (indirect calorimetry) and body temperature in CA (+45% and +1.1 degrees C) than in control ducklings (+30% and +0.4 degree C). In CA ducklings, the perfusion rate (thermal clearance method) and temperature of gastrocnemius increased (+130% and +1.0 degree C) shortly after glucagon, whereas tissue oxygenation (polarography) decreased (-34%). There was no significant effect of glucagon in TN controls. These changes, which peaked 45-60 min after glucagon injection, indicated a prolonged increase of muscle O2 consumption in CA ducklings. Leg muscle blood flow (radioactive microspheres) measured 45 min after glucagon was slightly increased in controls (+20%; P < 0.05), while in CA ducklings, the increase was larger (+76%; P < 0.05). The arteriovenous difference in O2 content was not markedly affected by glucagon in both groups. These parameters indicated an increase in leg muscle O2 uptake in response to glucagon of +29% in controls and +76% in CA ducklings. In controls, 28% of the GIC measured in vivo could be attributed to whole body skeletal muscles, compared with 53% in CA ducklings. The remaining part might be accounted for mostly by the liver.(ABSTRACT TRUNCATED AT 250 WORDS)

Acclimatization↗

PubMed1992

Autonomic nervous system response patterns correlate with mental imagery.

New findings related to autonomic nervous system (ANS) functions may reveal some brain functions, since they can be observed by real time analysis. ANS parameters (skin potential and resistance, skin temperature and blood flow, instantaneous heart rate) and instantaneous respiratory frequency are quantified by original techniques and indices. Results show that ANS responses correlate with mental imagery. Imagery contents influence autonomic responses, thus making it comparable to real activity. Therefore, by using two shooting events as models, the almost identical nature of the ANS response is evidenced during real shooting and in mental concentration before shooting. Next, shooting activity imagery can be distinguished from neutral imagery but is comparable to the activity itself as far as ANS responses are concerned.

Adult↗

PubMed1991

Relationship between mental imagery and sporting performance.

Simultaneous measurement of six autonomic nervous system (ANS) variable responses during mental rehearsal of an action, makes it possible to draw a parallel between mental imagery of a task and its actual execution. The experiment was carried out in the field during precision shooting competitions and in the laboratory for imagery activity, on 22 subjects. Results show that there is similarity of ANS response in the three situations: the period of concentration prior to shooting, actual shooting and mental representation of shooting. The ratio formed by ANS response during concentration and imagery of actual firing tends towards the value one, therefore towards some identity. All subjects may be classified around this value; it is worth noting that subject distribution around this value corresponds to performance value. It seems that the better the subject, the closer his concentration/shooting or imagery/actual shooting ratio is to the theoretical value one. These results show the utmost importance of the quality of mental representation for performance improvement. It can be supposed that subject classification above the theoretical value one corresponds to overflowing emotional reactivity in one of the two phases and that this interferes with accuracy; a placing below the theoretical value one shows a lack of similarity between mental representation and the action.

Adult↗

PubMed1991

The posterior hypothalamus is responsible for the increase of brain temperature during paradoxical sleep.

Electroencephalogram, caudate nucleus temperature (Tc), ear skin temperature (Te) as well as cerebral blood flow (CBF) measured by a thermal clearance method, were recorded simultaneously and continuously in cats. After baseline recording in which we confirmed the increase of Tc during paradoxical sleep (PS), neuronal cell bodies of the mesencephalic reticular formation and/or the posterior hypothalamus (PH) were destroyed with ibotenic acid. Only PH lesions were followed by either a suppression of the increase or even a decrease of Tc during PS while Te variations were not modified. The decrease in CBF, which was always associated with Tc increase, was suppressed after the PH lesion. These results led us to the conclusion that the increase of Tc at the onset of PS is due to a decrease in CBF. Furthermore, it may be hypothesized that the decrease in CBF depend upon an active vasoconstriction process originating in the PH.

Animals↗

PubMed1991

The effectiveness of Hernandia spp. (Hernandiaceae) in traditional Samoan medicine and according to scientific analyses.

The use of Hernandia nymphaefolia (Presl.) Kubitzki, Hernandia ovigera Linn., Hernandia peltata Meissner and Hernandia sonora Linn. in traditional Samoan medicine is given. The constituents have been listed and the effectiveness of the various plant parts deducted from them. A comparison of the traditional medicinal use with the assigned medicinal effectiveness shows clear concordances. Further pharmacological investigations are needed.

Alkaloids↗

PubMed1991

Fluid-shift during computer-modulated profile hemodialysis (CMP-HD).

Computer-modulated profile hemodialysis was examined for patients' comfort and fluid-shift. Fifteen patients were studied after two weeks of dialysis with each of the following profiles: A): constant ultrafiltration (UF) and dialysate sodium (138 mmol/l); B): decreasing UF; C): decreasing UF and decreasing high dialysate sodium (starting 10% above serum-sodium, with a gradual reduction to 138 mmol/l in the fourth hour). Patients with a calculated increase of intracellular volume (ICV) during dialysis had more complaints after dialysis than the others. ICV decreased in all patients with low serum-sodium (less than 136 mmol/l) during all profiles, whereas in patients with higher sodium, only profile C led to a decrease of ICV. However, interdialytic weight gain increased about 75% in patients with low serum-sodium under profile C. The sodium profile could help in preventing imbalance without side effects in patients with high sodium.

Aged↗